At the present time, most domestic roof s in North America are roofed or covered with shingles. Other roofing materials are known, such as wooden shakes and rigid tiles. Wooden shakes offer greater durability, but are relatively expensive and time consuming to lay. A variety of rigid tiles are gaining some popularity. For domestic use these are usually clay tiles. For industrial use they may be formed of concrete or other materials. Such rigid tiles will often be moulded with various ridges around their peripheries to prevent water leaking between adjacent tiles. However, such tiles are heavy and relatively expensive.
More recently a variety of synthetic roof and wall coverings have become known in the art. For example, there are panels formed of elongated thermoplastic panel elements that are nailed to the wall or roof support surface in horizontal courses or rows in partially overlapping relation to each other so as to provide a substantially water resistant, protective layer over the support surface. Such panels are usually identically moulded, and typically are formed with a plurality of rows of simulated building elements, such as shake shingles. In such panels, the individual building elements of each row commonly are moulded in laterally spaced relation with a separating groove therebetween. While it is desirable that the panels facilitate drainage of rain water and the like to which they are exposed in the outside environment, heretofore this has presented problems, since water can be drawn inwardly between overlapping marginal edge portions of adjacent panels and enter the space beneath the panels, either through nail holes or about the peripheral edges of the panels and become trapped and accumulate under the panels. Water movement can be caused by various factors, such as capillary action and pressure differences caused by wind. Such water movement worsens during high wind and storm conditions. Not only does the trapped moisture under the panels increase the possibility for leakage and damage to the wall or roof, but upon freezing, the expanding moisture tends to lift the overlapping edge portions further breaking the protective barrier between the panels and the support surface. When efforts have been made to prevent such capillary seepage between panels, they often have been ineffective, or have complicated the construction and cost of the panel, or have impeded the natural drainage of water from the panels.
A further difficulty with available building elements or tiles is that in practice they are difficult to assemble on the support surface.
To function properly as seals, the fit between overlapping panels must necessarily be exact and there is little or no flexibility to allow for inaccuracies in installation. For example, in U.S. Pat. No. 5,072,562 (Dec. 17, 1991) and U.S. Pat. No. 5,076,037 (Dec. 31, 1991) to Crick et al, assigned to Nailite International, the wall covering disclosed consists of an interlocking means which defines primary and secondary seals between the upper marginal edge region of the panel in one course and the overlapping lower marginal edge region of the panel in the course immediately above. This includes a top panel with a downturned lower peripheral lip which bears against the face of a ledge of the underlying panel thus establishing a primary seal; the underlying panel has an upper peripheral edge in the form of an upwardly turned sealing lip which can be positioned to engage with the underside of the lower marginal edge portion of the overlapping panel and establish a secondary seal. Between the two sealing means are provided additional water barrier means, namely a plurality of parallel barrier ridges in vertically spaced relation to one another which are integrally formed on the upper marginal region of each panel, and a pair of uninterrupted upstanding nail aperture guard ridges extending outwardly and which are integrally formed on the upper marginal panel.
In the commercial embodiment of the patents to Nailite, as known to the applicants interlocking means is provided consisting of an upper marginal edge region of a lower panel which is engaged by a plurality of downward-directed hooks which form part of the lower peripheral edge region of an upper panel in the course immediately above. The hook is adapted to engage the lower panel by insertion between the support surface and the upper portion of the upper marginal edge region of the lower panel, the upper portion being located above the nail aperture. The hook thus tends to pull the upper portion of the lower panel away from the support surface, and weaken the contact between the support surface and the lower panel, as well as to provide an area where water could gather between the support surface and the lower panel. Neither parallel barrier ridges nor nail guard aperture ridges are provided as disclosed in the patents. Further the additional seal provided by engagement of the lower peripheral lip of one panel with a ledge below the nail apertures of a panel below is omitted.
While such known panels are provided in large sizes to make installation easier, they are of relatively flimsy construction and include little support underneath. Consequently walking on the tiles would cause repeated flexing of the tile, and possibly could eventually crack the tile.
It is an object of the present invention to provide wall and roof tile panels which are adapted for easy alignment and mounting through simple interlocking means, such that successive courses of panels can be quickly and easily mounted on the support surface. It is also desirable that any interlocking arrangement should not interfere with the mounting provided by an upper row of nail apertures and further preferably includes any additional water barrier.
Such tiles should be capable of being moulded simply and economically in a plastic or synthetic material, and should be configured to provide good support any person walking on them.